The Experts below are selected from a list of 6495 Experts worldwide ranked by ideXlab platform
Dan Stamperkurn - One of the best experts on this subject based on the ideXlab platform.
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condensing magnons in a degenerate ferromagnetic spinor bose gas
Physical Review Letters, 2016Co-Authors: Fang Fang, Holger Kadau, Shun Wu, Dan StamperkurnAbstract:: We observe the quasicondensation of magnon excitations within an F=1 ^{87}Rb spinor Bose-Einstein condensed gas. Magnons are pumped into a ferromagnetically ordered gas, allowed to equilibrate to a nondegenerate distribution, and then cooled evaporatively at near-constant net Longitudinal Magnetization, whereupon they condense. The critical magnon number, spatial distribution, and momentum distribution indicate that magnons condense in a potential that is uniform within the volume of the ferromagnetic condensate. The macroscopic transverse Magnetization produced by the degenerate magnon gas remains inhomogeneous within the ∼10 s equilibration time accessed in our experiment, and includes signatures of Mermin-Ho spin textures that appear as phase singularities in the magnon quasicondensate wave function.
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condensing magnons in a degenerate ferromagnetic spinor bose gas
Physical Review Letters, 2016Co-Authors: Fang Fang, Holger Kadau, Shun Wu, Dan StamperkurnAbstract:: We observe the quasicondensation of magnon excitations within an F=1 ^{87}Rb spinor Bose-Einstein condensed gas. Magnons are pumped into a ferromagnetically ordered gas, allowed to equilibrate to a nondegenerate distribution, and then cooled evaporatively at near-constant net Longitudinal Magnetization, whereupon they condense. The critical magnon number, spatial distribution, and momentum distribution indicate that magnons condense in a potential that is uniform within the volume of the ferromagnetic condensate. The macroscopic transverse Magnetization produced by the degenerate magnon gas remains inhomogeneous within the ∼10 s equilibration time accessed in our experiment, and includes signatures of Mermin-Ho spin textures that appear as phase singularities in the magnon quasicondensate wave function.
Bernhard Blümich - One of the best experts on this subject based on the ideXlab platform.
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residual dipolar couplings by 1h dipolar encoded Longitudinal Magnetization double and triple quantum nuclear magnetic resonance in cross linked elastomers
Journal of Chemical Physics, 1999Co-Authors: Michael Schneider, Dan E. Demco, L Gasper, Bernhard BlümichAbstract:The measurements of residual dipolar couplings in elastomer system is desirable, because they reflect the hindrance to molecular motions by the cross-linking, topological constraints and the external factors like mechanical stress. Dipolar-encoded Longitudinal Magnetization nuclear magnetic resonance (NMR) decay curves, double-quantum and triple-quantum NMR buildup intensities for measuring the residual dipolar couplings, and the associated dynamic order parameters are introduced. It is shown that in the short excitation time regime the effective dipolar network is simplified. In the limit of this model based on localized dipolar couplings, the spin response to two-dimensional pulse sequences used to record multiple-quantum (MQ) NMR coherences was evaluated for Longitudinal Magnetization, double-, and triple-quantum coherences of methylene, and methyl protons in synthetic 1,4-cis-polyisoprene. The dynamic order parameters can be evaluated from this NMR response using a classical scale-invariant polymer mo...
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1H NMR imaging of residual dipolar couplings in cross-linked elastomers: dipolar-encoded Longitudinal Magnetization, double-quantum, and triple-quantum filters.
Journal of magnetic resonance (San Diego Calif. : 1997), 1999Co-Authors: Michael Schneider, Dan E. Demco, Bernhard BlümichAbstract:Contrastfilters for NMR imaging of residual 1H dipolar couplings of elastomers are introduced based on dipolar-encoded Longitudinal Magnetization, as well as double- and triple-quantum coherences. The spin response is discussed in the initial excitation time regime for methylene, methyl, and methine protons applicable to poly(isoprene) and other elastomers, taking into account the hierarchy of dipolar couplings and the associated editing features of multiple-quantum experiments. The efficiency of these filters is investigated for a series of cross-linked poly(isoprene) samples. Spatially resolved dipolar-encoded Longitudinal Magnetization decays and double-quantum and triple-quantum buildup curves are presented for a phantom made of poly(isoprene) with different cross-link densities. Two-dimensional images representing residual dipolar couplings are presented using dipolar-encoded Longitudinal Magnetization, double-quantum, and triple-quantum contrast filters. Images from dipolar-encoded Longitudinal Magnetization and triple-quantum coherences show the highest resolution and contrast, respectively.
Jianying Zhou - One of the best experts on this subject based on the ideXlab platform.
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all optically configuring the inverse faraday effect for nanoscale perpendicular magnetic recording
Optics Express, 2015Co-Authors: Sicong Wang, Jianying ZhouAbstract:Nanoscale reversal of the Longitudinal Magnetization (Mz) is highly desired in the ultrahigh density perpendicular magnetic recording. In this paper, an all-optical method to realize the reversal of Mz with an ultrasmall lateral size through configuring the inverse Faraday effect (IFE) is numerically proposed. This feature is achieved by optical coherent configuration of the IFE in the central and peripheral regions of the focal spot with opposite signs. By increasing the intensity of the peripheral regions to produce destructive interference, the lateral size of the reversed Mz smaller than 30 nm in one dimension in the central region can be achieved. This result is of vital importance for realizing ultrafast nanoscale perpendicular magnetic recording.
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ultralong pure Longitudinal Magnetization needle induced by annular vortex binary optics
Optics Letters, 2014Co-Authors: Sicong Wang, Jianying ZhouAbstract:In this Letter, based on the Richards and Wolf diffraction theory, an ultralong optical needle with pure transverse polarization is numerically generated by tightly focusing an azimuthally polarized beam through an annular vortex binary filter. Such an ultralong transversely polarized optical needle is generated through the π phase shift between adjacent rings of the binary filter. We show that such a pure transverse optical needle can induce pure Longitudinal Magnetization with a subwavelength lateral size (0.38λ) and an ultralong Longitudinal depth (7.48λ) through the inverse Faraday effect. The corresponding needle aspect ratio of 20 is twice as large as that of the Longitudinal Magnetization needle generated by electron beam lithography.
Ying Lin Song - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal Magnetization superoscillation enabled by high order azimuthally polarized laguerre gaussian vortex modes
Optics Express, 2021Co-Authors: Xiao Fei Liu, Zhong Quan Nie, Ying Lin Song, Weichao Yan, Yue Liang, Yuxiao Wang, Zehui Jiang, Xue Ru ZhangAbstract:We present an all-optical scheme for the generation of Longitudinal Magnetization superoscillation based on the vectorial diffraction theory and the inverse Faraday effect. To achieve this, an azimuthally polarized high-order Laguerre–Gaussian vortex mode is firstly focused by a high numerical aperture (NA) objective and then impinges on an isotropic magneto-optical material. It is found that, by judiciously controlling the intrinsic arguments (radial mode index (p) and truncation parameter (β)) of such a configurable vectorial vortex beam, the Longitudinal magnetic domain induced in the focal plane can be switched from a peak sub-wavelength Magnetization (> 0.36λ/NA), via the fastest Fourier Magnetization component (∼0.36λ/NA), to a super-oscillation Magnetization hotspot (< 0.36λ/NA). We further examine the dependence of the transverse size, the side lobe, and the energy conversion efficiency within the focal Magnetization domain on both the p and β of the initial vortex modes, confirming that the higher-order structured vortex beams are preferable alternatives to trigger robust Longitudinal Magnetization superoscillation. In addition, the underlying mechanisms behind the well-defined Magnetization phenomena are unveiled. The ultra-small-scale Longitudinal Magnetization demonstrated here may hold massive potential applications in high-density all-optical magnetic recording/storage, super-resolution magnetic resonance imaging, atom trapping and spintronics.
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three dimensional super resolution Longitudinal Magnetization spot arrays
Light-Science & Applications, 2017Co-Authors: Zhong Quan Nie, Han Lin, Xiao Fei Liu, Ai Ping Zhai, Yan Ting Tian, Wen Jie Wang, Weiqiang Ding, Xue Ru Zhang, Ying Lin Song, Bao Hua JiaAbstract:We demonstrate an all-optical strategy for realizing spherical three-dimensional (3D) super-resolution (∼λ3/22) spot arrays of pure Longitudinal Magnetization by exploiting a 4π optical microscopic setup with two high numerical aperture (NA) objective lenses, which focus and interfere two modulated vectorial beams. Multiple phase filters (MPFs) are designed via an analytical approach derived from the vectorial Debye diffraction theory to modulate the two circularly polarized beams. The system is tailored to constructively interfere the Longitudinal Magnetization components, while simultaneously destructively interfering the azimuthal ones. As a result, the Magnetization field is not only purely Longitudinal but also super-resolved in all three dimensions. Furthermore, the MPFs can be designed analytically to control the number and locations of the super-resolved Magnetization spots to produce both uniform and nonuniform arrays in a 3D volume. Thus, an all-optical control of all the properties of light-induced Magnetization spot arrays has been demonstrated for the first time. These results open up broad applications in magnetic-optical devices such as confocal and multifocal magnetic resonance microscopy, 3D ultrahigh-density magneto-optic memory, and light-induced magneto-lithography. A scheme for making 3D arrays of subwavelength Magnetization spots will benefit the high-density data storage and magnetic resonance microscopy. Zhong-Quan Nie and co-workers used two high-numerical-aperture lenses to focus and interfere a pair of circularly polarized Bessel Gaussian beams. They used spatial light modulators to modulate the wavefronts of the two beams in such a way that enhanced Longitudinal Magnetization components through constructive interference and simultaneously cancelled the azimuthal components by deconstructive interference. This generated an array of super-resolution spots of pure Longitudinal Magnetization. The number and location of the spots can be varied by changing the signal sent to the spatial light modulator. This is the first demonstration of all-optical control of all the properties of light-induced Magnetization spot arrays and is promising for developing the light-induced magnetic data storage and lithography devices.
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achievement and steering of light induced sub wavelength Longitudinal Magnetization chain
Optics Express, 2015Co-Authors: Zhong Quan Nie, Weiqiang Ding, Xue Ru Zhang, Yuxiao Wang, Guang Shi, Ying Lin SongAbstract:The light-induced Magnetization distributions for a high numerical aperture focusing configuration with an azimuthally polarized Bessel-Gaussian beam modulated by optimized vortex binary filters are investigated based on the inverse Faraday effect. It is found that, by adjusting the radii of different rings of the single/ cascaded vortex binary filters, super-long (12λ) and sub-wavelength (0.416λ) Longitudinal Magnetization chain with single/dual channels can be achieved in the focal region. Such well-behaved Magnetization trait is attributed to the mutual effect between the optical polarization singularities of the azimuthally polarized beam and single/cascaded spiral optical elements. In addition, we find that the displacement distance of the Longitudinal Magnetization chain is proportional to the phase difference between the inner circle and outer ring of the vortex binary filters, thus giving rise to the steerable Magnetization chain. It is expected that the research outcomes can be applied in multiple atoms trapping and transport, multilayer magneto-optical data storage, fabrication of magnetic lattices for spin wave operation and development of ultra-compact optomagnetic devices.
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spherical and sub wavelength Longitudinal Magnetization generated by 4π tightly focusing radially polarized vortex beams
Optics Express, 2015Co-Authors: Zhong Quan Nie, Weiqiang Ding, Xue Ru Zhang, Yuxiao Wang, Ying Lin SongAbstract:Based on the vector diffraction theory and the inverse Faraday effect, we numerically study the light-induced Magnetization near the focus of a 4π high numerical aperture focusing configuration under the illumination of two counter- propagating radially polarized hollow Gaussian vortex beams. The simulated results demonstrate that, by selecting higher-order vortex beam modes (e.g. n=4with n - the beam order) and proper truncation parameter (e.g. β=1.75 with β- the ratio of the pupil radius to the incident beam waist), spherical and sub-wavelength Longitudinal Magnetization can be generated in the vicinity of focus. Such special Magnetization feature is attributed to not only the interaction between optical vortices and the radially polarized beams, but also the completely destructive interference of azimuthal components and the constructive interference of the Longitudinal component of the two counter-propagating radially polarized vortex beams. This spherical and sub-wavelength Longitudinal Magnetization distribution may be of interest for applications in all-optical magnetic recording and confocal and magnetic resonance microscopy.
Irving J Lowe - One of the best experts on this subject based on the ideXlab platform.
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encoding to the Longitudinal Magnetization for mr imaging and flow velocity mapping
Journal of Magnetic Resonance, 2006Co-Authors: Jungjiin Hsu, Irving J LoweAbstract:Abstract Phase-encoding to the Longitudinal Magnetization is implemented by adding encoding gradient pulses in the evolution period τ of the NMR pulse sequence 90 ° + x – τ – 90 ° - x . This work focuses on the effect of the spin–lattice relaxation and its removal and on the constraint that the 90 ° - x pulse can only transform the phase of the transverse Magnetization partially to the Longitudinal Magnetization. Theoretical analysis shows that the encoded phase information and the spin–lattice relaxation effect are separable and the latter is identical in each repetition in collecting phase-encoding data. Thus the relaxation effect can be eliminated by subtracting a second data set whose phase information is inverted or by alternating the polarity of the relaxation contribution. From data with partial phase information, Fourier-transform image reconstruction results in mirror aliasing in which the two halves of the Fourier spectrum of positive and negative coordinates overlap. Removal of mirror aliasing requires imaging data of the orthogonal component. Nevertheless mirror aliasing is not necessarily a problem, depending on the subject of study. Phase-encoding to the Longitudinal Magnetization for spatial MRI and flow velocity mapping are demonstrated using the rotating ultra-fast imaging sequence (RUFIS).
